Overhang Design Methods: Optimal Thermal and Daylighting Performance

Description

It is estimated that windows in office buildings are responsible for one third of energy used for their heating and cooling. Designing window shading that balances often contradictory goals of preventing excessive heat gains in hot periods, without compromising beneficial heat gains in cold periods or visual comfort in indoor spaces of modern buildings with highly glazed facades, is an interesting multi-objective optimisation problem that represents an active research topic in the field of building energy and daylighting. Window overhangs are the simplest and most traditional shading devices that are easy to install, highly cost-effective, require low or no maintenance and offer unobstructed views outside. This book provides a review of overhang design methods for optimal thermal and daylighting performance. It starts with a historical overview of methods based on solar positions and shading masks. Next it discusses current research methodology, including shading calculation methods, ways of quantifying thermal and daylighting overhang effectiveness and the use of multi-objective optimisation approaches, together with the case studies that employ them. It further covers methods for designing innovative overhang types such as NURBS outlined overhangs and PV integrated dynamic overhangs. The appendix classifies published overhang case studies according to major climate type and latitude of their locations. As such, the book presents a valuable resource for understanding subtle nuances of interaction between solar radiation, shading devices and indoor comfort. The intended target audience are building energy researchers interested in optimisation of window shading devices.​ Contents 1 Introduction References 2 Solar Path Methods 2.1 Olgyays' Horizontal Projection Method 2.2 Mazria's Cylindrical Projection Method 2.3 Backward Tracing of the Solar Rays References 3 Current Overhang Research Methodology 3.1 Simulation Methods 3.1.1 Methods Developed Particularly for Overhangs 3.1.2 Methods for General Shading Calculations 3.1.3 Grouping of Solar Positions in Shading Calculations 3.1.4 Sensitivity Analysis of Shading Calculations 3.2 What to Measure? 3.2.1 Thermal Performance Indicators 3.2.2 Daylighting Performance Indicators 3.3 Optimisation Approaches 3.3.1 Pareto Front 3.3.2 Genetic Algorithms References 4 Design Methods for Particular Overhang Types 4.1 Subdividing Shading Support Surface 4.2 NURBS Outlined Overhangs 4.3 Trimming Windows to Fit the Overhang 4.4 Shading Retrofits 4.5 PV Integrated and Movable Overhangs References Appendix Locations and Climates of Overhang Case Studies References